This invention relates to a device for use in a refueling opening and, more particularly, to a sealing device for use in a refueling opening of a motor vehicle or the like at the time of refueling in order to prevent leakage of fuel and substances evaporating from the fuel.
In general, a refueling opening of a fuel tank is not provided with a sealing device for preventing substances evaporating from a fuel from escaping from the tank at the time of refueling. There is therefore a problem of evaporating substances being released to the atmosphere at the time of refueling, and there is a demand for a sealing device adapted to the fueling opening.
The inventor of the present invention has studied sealing devices for use in refueling openings and has found that a sealing device is required to satisfy the following conditions.
That is, it is desirable for the sealing device to closely contact the fueling nozzle at the time of refueling to prevent any fuel substances from being released to the atmosphere; to have a relief mechanism in order to prevent the pressure inside the fuel tank from increasing higher than a predetermined level in a case where the pressure inside the fuel tank excessively increases because the vapor of fuel substances is not released to the atmosphere; and to be capable of allowing the fueling nozzle to be inserted or drawn out with a constant load even if a portion in contact with the fuel substances and the vapor formed therefrom swells or shrinks.
The inventor had first developed a sealing device for use in a refueling opening, such as the one shown in FIGS. 6 to 9.
This sealing device for a refueling opening is constructed in such a manner that a seal retaining member 42 is disposed inside a casing 41 in the form of a tube disposed in a refueling opening (not shown), an elastic seal member 43 in the form of a ring being fixed to the seal retaining member 42. A nozzle guide member 45 for guiding a fueling nozzle 44 when the fueling nozzle 44 is inserted into the casing is also attached to the seal retaining member 42.
At the time of insertion of the fueling nozzle 44, the elastic seal member 43 effects sealing between itself and the fueling nozzle 44.
This type of sealing device for use in a refueling opening was manufactured by way of trial and was tested by experiment, and the following problems were found.
That is, influences of fuel and substances evaporating the fuel upon the swelling or shrinkage of the elastic seal member 32 appear as changes in the inside diameter D.sub.1 of the elastic seal member 43 because the outer peripheral surface of a sealing portion of the elastic seal member 43 for effecting sealing with the fueling nozzle 44 is retained over its entire area by the seal retaining member 42.
It is necessary for the elastic seal member 43 to effect sealing between itself and the fueling nozzle 44 in conformity with the outside diameter of the fueling nozzle 44 which may vary in a certain range of dispersion, and the squeeze (which is determined the inside diameter D.sub.1 of the elastic seal member 43 with which the fueling nozzle 44 is fastened see FIG. 7) is set in such a manner that the elastic seal member 43 can be brought into close contact with the fueling nozzle 44 even if the outside diameter thereof is minimum. As a result, the squeeze of fastening is excessively large when the nozzle diameter is maximum, and it further increases by the influence of swelling.
If the squeeze of fastening is increased in this manner, in other words, the elastic seal member 43 expands to a certain extent while the nozzle diameter is large, it is difficult to insert the fueling nozzle 44 into the elastic seal member 43. If, conversely, the nozzle diameter is minimum, there is a possibility of considerable deterioration of the sealing performance.